The Effect of Distinct Geometric Semantic Crossover Operators in Regression Problems

This paper investigates the impact of geometric semantic crossover operators in a wide range of symbolic regression problems. First, it analyses the impact of using Manhattan and Euclidean distance geometric semantic crossovers in the learning process. Then, it proposes two strategies to numerically optimize the crossover mask based on mathematical properties of these operators, instead of simply generating them randomly. An experimental analysis comparing geometric semantic crossovers using Euclidean and Manhattan distances and the proposed strategies is performed in a test bed of twenty datasets. The results show that the use of different distance functions in the semantic geometric crossover has little impact on the test error, and that our optimized crossover masks yield slightly better results. For SGP practitioners, we suggest the use of the semantic crossover based on the Euclidean distance, as it achieved similar results to those obtained by more complex operators

Alternative pathways for angiotensin II generation in the cardiovascular system

The classical renin-angiotensin system (RAS) consists of enzymes and peptides that regulate blood pressure and electrolyte and fluid homeostasis. Angiotensin II (Ang II) is one of the most important and extensively studied components of the RAS. The beneficial effects of angiotensin converting enzyme (ACE) inhibitors in the treatment of hypertension and heart failure, among other diseases, are well known. However, it has been reported that patients chronically treated with effective doses of these inhibitors do not show suppression of Ang II formation, suggesting the involvement of pathways alternative to ACE in the generation of Ang II. Moreover, the finding that the concentration of Ang II is preserved in the kidney, heart and lungs of mice with an ACE deletion indicates the important role of alternative pathways under basal conditions to maintain the levels of Ang II. Our group has characterized the serine protease elastase-2 as an alternative pathway for Ang II generation from Ang I in rats. A role for elastase-2 in the cardiovascular system was suggested by studies performed in heart and conductance and resistance vessels of normotensive and spontaneously hypertensive rats. This mini-review will highlight the pharmacological aspects of the RAS, emphasizing the role of elastase-2, an alternative pathway for Ang II generation

Mutations of Bruton's tyrosine kinase gene in Brazilian patients with X-linked agammaglobulinemia

Mutations in Bruton's tyrosine kinase (BTK) gene are responsible for X-linked agammaglobulinemia (XLA), which is characterized by recurrent bacterial infections, profound hypogammaglobulinemia, and decreased numbers of mature B cells in peripheral blood. We evaluated 5 male Brazilian patients, ranging from 3 to 10 years of age, from unrelated families, whose diagnosis was based on recurrent infections, markedly reduced levels of IgM, IgG and IgA, and circulating B cell numbers <2%. BTK gene analysis was carried out using PCR-SSCP followed by sequencing. We detected three novel (Ala347fsX55, I355T, and Thr324fsX24) and two previously reported mutations (Q196X and E441X). Flow cytometry revealed a reduced expression of BTK protein in patients and a mosaic pattern of BTK expression was obtained from mothers, indicating that they were XLA carriers

Revisiting the Sequential Symbolic Regression Genetic Programming

Sequential Symbolic Regression (SSR) is a technique that recursively induces functions over the error of the current solution, concatenating them in an attempt to reduce the error of the resulting model. As proof of concept, the method was previously evaluated in one-dimensional problems and compared with canonical Genetic Programming (GP) and Geometric Semantic Genetic Programming (GSGP). In this paper we revisit SSR exploring the method behaviour in higher dimensional, larger and more heterogeneous datasets. We discuss the difficulties arising from the application of the method to more complex problems, e.g., overfitting, along with suggestions to overcome them. An experimental analysis was conducted comparing SSR to GP and GSGP, showing SSR solutions are smaller than those generated by the GSGP with similar performance and more accurate than those generated by the canonical GP

Mutations of bruton's tyrosine kinase gene in Brazilian patients with X-linked agammaglobulinemia

Mutations in Bruton's tyrosine kinase (BTK) gene are responsible for X-linked agammaglobulinemia (XLA), which is characterized by recurrent bacterial infections, profound hypogammaglobulinemia, and decreased numbers of mature B cells in peripheral blood. We evaluated 5 male Brazilian patients, ranging from 3 to 10 years of age, from unrelated families, whose diagnosis was based on recurrent infections, markedly reduced levels of IgM, IgG and IgA, and circulating B cell numbers <2%. BTK gene analysis was carried out using PCR-SSCP followed by sequencing. We detected three novel (Ala347fsX55, I355T, and Thr324fsX24) and two previously reported mutations (Q196X and E441X). Flow cytometry revealed a reduced expression of BTK protein in patients and a mosaic pattern of BTK expression was obtained from mothers, indicating that they were XLA carriers439COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2008/54220-

Reducing Dimensionality to Improve Search in Semantic Genetic Programming

Genetic programming approaches are moving from analysing the syntax of individual solutions to look into their semantics. One of the common definitions of the semantic space in the context of symbolic regression is a n-dimensional space, where n corresponds to the number of training examples. In problems where this number is high, the search process can became harder as the number of dimensions increase. Geometric semantic genetic programming (GSGP) explores the semantic space by performing geometric semantic operations—the fitness landscape seen by GSGP is guaranteed to be conic by construction. Intuitively, a lower number of dimensions can make search more feasible in this scenario, decreasing the chances of data overfitting and reducing the number of evaluations required to find a suitable solution. This paper proposes two approaches for dimensionality reduction in GSGP: (i) to apply current instance selection methods as a pre-process step before training points are given to GSGP; (ii) to incorporate instance selection to the evolution of GSGP. Experiments in 15 datasets show that GSGP performance is improved by using instance reduction during the evolution

A prática profissional integradano curso de licenciatura em química: uma possibilidade de formação do professor reflexivo

Os debates atuais sobre a formação docente apontam a necessidade de romper com o modelo tradicionalde sólida base teórica de conteúdos específicos e pedagógicosdesconectados da reflexão ou ação na prática docente.A elaboração e desenvolvimento de propostas curriculares inovadoras, ao longo dos cursos de licenciaturaque visam à formação do professor reflexivo, acompanhados pela pesquisa, possibilitam avanços tanto nos licenciandos como nos docentes formadores. As entrevistas com docentes e licenciandos e as aulas dos licenciandos foram videogravadas, transcritas e analisadas pela Análise Textual Discursiva.A análise dos dados coletadospermite apontar alguns avanços nas concepções dos integrantes da pesquisa, estabelecidos pela dinâmica de formação proposta, na direção de constituição do professor reflexivo

A Generic Framework for Building Dispersion Operators in the Semantic Space

This chapter proposes a generic framework to build geometric dispersion (GD) operators for Geometric Semantic Genetic Programming in the context of symbolic regression, followed by two concrete instantiations of the framework: a multiplicative geometric dispersion operator and an additive geometric dispersion operator. These operators move individuals in the semantic space in order to balance the population around the target output in each dimension, with the objective of expanding the convex hull defined by the population to include the desired output vector. An experimental analysis was conducted in a testbed composed of sixteen datasets showing that dispersion operators can improve GSGP search and that the multiplicative version of the operator is overall better than the additive version

The activation of α1-adrenoceptors is implicated in the antidepressant-like effect of creatine in the tail suspension test

AbstractThe antidepressant-like activity of creatine in the tail suspension test (TST) was demonstrated previously by our group. In this study we investigated the involvement of the noradrenergic system in the antidepressant-like effect of creatine in the mouse TST. In the first set of experiments, creatine administered by i.c.v. route (1μg/site) decreased the immobility time in the TST, suggesting the central effect of this compound. The anti-immobility effect of peripheral administration of creatine (1mg/kg, p.o.) was prevented by the pretreatment of mice with α-methyl-p-tyrosine (100mg/kg, i.p., inhibitor of tyrosine hydroxylase), prazosin (1mg/kg, i.p., α1-adrenoceptor antagonist), but not by yohimbine (1mg/kg, i.p., α2-adrenoceptor antagonist). Creatine (0.01mg/kg, subeffective dose) in combination with subeffective doses of amitriptyline (1mg/kg, p.o., tricyclic antidepressant), imipramine (0.1mg/kg, p.o., tricyclic antidepressant), reboxetine (2mg/kg, p.o., selective noradrenaline reuptake inhibitor) or phenylephrine (0.4μg/site, i.c.v., α1-adrenoceptor agonist) reduced the immobility time in the TST as compared with either drug alone. These results indicate that the antidepressant-like effect of creatine is likely mediated by an activation of α1-adrenoceptor and that creatine produces synergistic effects in the TST with antidepressants that modulate noradrenaline transporter, suggesting that an improvement in the response to the antidepressant therapy may occur when creatine is combined with these antidepressants. Furthermore, the synergistic effect of creatine (0.01mg/kg, p.o.) and reboxetine (2mg/kg, p.o.) combination was abolished by the α1-adrenoceptor antagonist prazosin, indicating that the antidepressant-like effect of combined therapy is likely mediated by an activation of α1-adrenoceptor

PREFERÊNCIA DE EQÜINOS EM PASTEJO: EFEITO DA ALTURA DE DOSSÉIS DE GRAMÍNEAS DO GÊNERO CYNODON

The experiment was conducted at the experimental farm of the Federal University of Paraná, in February, 1998, and investigated the effect of the different Cynodon grasses structure at the horse grazing. The Cynodon spp. cv Tifton 85, Cynodon nlemfuensis cv Tifton 68, Cynodon spp. cv Tifton 44, Cynodon nlemfuensis (¨Porto Rico¨) and Cynodon nlemfuensis (¨Estrela Roxa¨) grasses were distributed in parcels with 12 m2 in a completely randomized split-plot design with four replications. The parcels were divided in two kinds of patches (tall and short) demonstrated by plants height. Five grazing tests were done with mares, evaluating the number of bites allocated in each treatment. The preference was evaluated by bite number and tiller grazed on each treatment. The bite depth was measured using 20 marked tillers in each experimental unit. The animals showed preference for Tifton 85, followed by Coastcross 1, Tifton 68 and Tifton 44. The star grasses ¨Estrela Roxa¨ and ¨Porto Rico¨ were not preferred. Tifton 85 and Coastcross 1 with more leaves and less stems mass (PO experimento foi conduzido no Centro de Estações Experimentais da Universidade Federal do Paraná, em fevereiro de 1998, quando as gramíneas Cynodon spp. cv Tifton 85, Cynodon nlemfuensis cv Tifton 68, Cynodon spp. cv Tifton 44, Cynodon nlemfuensis (Porto Rico) e Cynodon nlemfuensis (Estrela Roxa) foram estabelecidas em parcelas em um delineamento inteiramente casualizado com parcelas subdivididas e quatro repetições. As parcelas foram subdivididas em duas alturas do dossel (alto e baixo) caracterizadas pela diferença de altura das plantas. Os tratamentos foram ofertados a três éguas por duas horas em cinco dias consecutivos. A preferência entre os tratamentos foi identificada pela avaliação do número de bocados e pela desfolha nas unidades vegetativas marcadas nas parcelas e alturas. A profundidade do bocado foi quantificada por meio da identificação da altura do perfilho estendido e da menor altura pastejada nos perfilhos marcados das diferentes gramíneas. A Tifton 85 foi preferida, seguida pela Coastcross 1, Tifton 68 e Tifton 44. A Estrela Roxa e a Porto Rico foram preteridas. As gramíneas de maior preferência apresentavam maior massa de folhas verdes em relação à massa de colmos (